EP0096985A1 - Revêtement de creuset et procédé de fabrication ainsi que son utilisation - Google Patents

Revêtement de creuset et procédé de fabrication ainsi que son utilisation Download PDF

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Publication number
EP0096985A1
EP0096985A1 EP83302991A EP83302991A EP0096985A1 EP 0096985 A1 EP0096985 A1 EP 0096985A1 EP 83302991 A EP83302991 A EP 83302991A EP 83302991 A EP83302991 A EP 83302991A EP 0096985 A1 EP0096985 A1 EP 0096985A1
Authority
EP
European Patent Office
Prior art keywords
liner
alkaline earth
crucible
pouring
refractory
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83302991A
Other languages
German (de)
English (en)
Inventor
Gowri S. Jayaraman
James S. Perron
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northrop Grumman Space and Mission Systems Corp
Original Assignee
TRW Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TRW Inc filed Critical TRW Inc
Publication of EP0096985A1 publication Critical patent/EP0096985A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/10—Monolithic linings; Supports therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/08—Details peculiar to crucible or pot furnaces
    • F27B14/10—Crucibles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/16—Making or repairing linings increasing the durability of linings or breaking away linings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/08—Details peculiar to crucible or pot furnaces
    • F27B14/10—Crucibles
    • F27B2014/104—Crucible linings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics

Definitions

  • the present invention relates to a new and improved crucible liner and a method by which the liner is made and used to promote the adherence of reaction products on the inner side surface of the liner during pouring of molten, metal from the liner.
  • Nickel chrome super alloys are commonly used for the forming of vanes and blades used in gas turbine engines. When a nickel chrome alloy is melted in a crucible, the alloy reacts with the refractory materials of the crucible liner. This interaction results in the formation of reaction products or waste materials. When the molten metal is poured out of the crucible, these reaction .products tend to flow along with the molten metal into the mold. The reaction products promote the formation of defects in a cast article.
  • the present invention provides a new and improved crucible liner which promotes the tight adherence of a relatively thick reaction layer to the inside of the liner during pouring of a nickel chrome alloy.
  • the liner is formed of a refractory material and is impregnated with an alkaline earth.
  • the refractory liner may be impregnated with the alkaline earth by quickly pouring an aqueous solution of the alkaline earth into and out of the liner.
  • the alloy When a nickel chrome alloy is melted in the crucible liner, the alloy reacts with both the alkaline earth and the refractory material of the liner. An interaction occurs between the alloy, the alkaline earth and the refractory material to form a relatively thick layer of reaction product on the side surface of the liner. The layer of reaction product adheres tightly to the surface of the liner. This prevents the reaction product from entering a mold.
  • Another object of this invention is to provide a new and improved crucible liner which is formed by wetting the inside of a refractory liner with an alkaline earth solution.
  • Another object of this invention is to provide a new and improved method which includes providing an interaction between a molten nickel chrome alloy, an alkaline earth and a refractory material of a crucible liner to maintain a relatively thick layer of reaction product on an inside surface of the liner during pouring of the molten alloy.
  • a new and improved liner 10 which is adapted to be placed inside a crucible in a manner similar to that disclosed in U.S. Patent No. 3,401,227.
  • a generally cylindrical cavity 12 inside the refractory liner 10 is partially filled with a nickel chrome alloy.
  • the alloy is melted in a known manner by an induction coil.
  • the molten nickel chrome alloy is then poured from the crucible into a mold to cast an article, such as a gas turbine component.
  • the alloy when a nickel chrome alloy is melted in the crucible liner 10, the alloy interacts with both the refractory materials of the liner and an alkaline earth with which the liner has been impregnated.
  • the reaction products are deposited on the inside of the liner.
  • the reaction products adhere to the inner side surface 11 of the liner and form a relatively thick reaction layer. This prevents the reaction products from entering a mold. By reducing the amount of impurities which enter the mold, the formation of defects in a cast article tends to be minimized.
  • the crucible liner 10 has a cylindrical refractory side wall 16 which extends upwardly from a circular bottom section 18 to an annular lip 20. If desired, the lip 20 could be shaped to promote the pouring of molten metal over a particular portion of the lip. Although the crucible liner 10 has a generally cylindrical configuration, it is contemplated that the crucible liner could have a different configuration if desired.
  • the crucible liner 10 is formed of a refractory material such as fused silica, zircon and/or other materials in combination with suitable binders.
  • the crucible liner 10 is made by repetitively dipping a pattern into a slurry of ceramic mold material.
  • slurry of ceramic mold material.
  • slurry contained fused silica, zircon, and other refractory materials in combination with binders.
  • Chemical binders such as ethyl silicate, sodium silicate and colloidal silica can be used if desired.
  • the slurry may contain suitable film formers such as alginates to control viscosity and wetting -agents to control flow characteristics and pattern wettability.
  • the crucible liner 10 was formed by first making a cylindrical aluminum plug which was covered with a wax coating to form a pattern. An initial slurry coating was applied to the pattern.
  • the initial slurry coating contained a finely divided refractory material to produce an accurate surface finish.
  • This initial slurry coating contained colloidal silica suspension, zircon and a relatively small amount of a wetting agent.
  • the surface was stuccoed with refractory materials. After stuccoing, the coating was dried and again dipped and stuccoed. The pattern was repetitively dipped and dried enough times to build up a covering of ceramic mold material of a desired thickness. The manner in which this was done is similar to that disclosed in U.S. Patent No. 3,401,227. After a covering of a desired thickness has been built up, the pattern is separated from the liner. The liner is then fired to about 1500-1800°F for one hour to remove residual pattern wax and strengthen the shell.
  • the residual pattern wax can be removed without firing the liner. This can be done by removing the residual pattern wax from the green or unfired mold with a known solvent such as trichloroethylene which is used to dissolve the residual pattern wax.
  • the liner 10 is impregnated with an alkaline earth.
  • an aqueous solution of the alkaline earth is prepared.
  • the alkaline earth solution is quickly poured into a liner 10.
  • the solution is immediately poured out of the liner without allowing for any soaking time. If the residual pattern wax is removed by firing the liner, the liner will not be green when the alkaline earth solution is poured into and out of it. However, if a solvent is used to remove the residual pattern wax, the liner will be green when the alkaline earth solution is poured into and out of the liner.
  • the wet refractory liner 10 is then at least partially dried. After a drying period, the alkaline earth treated liner 10 is fired. This may be either the first or second firing of the liner depending upon how the residual pattern wax is removed.
  • the fired liner 10 is impregnated with the alkaline earth and is ready for use in a crucible. It is contemplated that the firing of the liner may take place as the crucible is heated immediately prior to melting the molten metal in the crucible.
  • the liner 10 was treated with the alkaline earth calcium.
  • an aqueous calcium nitrate solution was prepared.
  • the calcium nitrate - solution contained approximately 1.7 grams of hydrated calcium nitrate (Ca(NO 3 ) 2 .4H 2 O) per cc of solvent.
  • the solution was prepared by gradually adding 4,000cc of distilled water to 15 lbs. of hydrated calcium nitrate. The solution was stirred until the calcium salt completely dissolved in the water. If the solution is dirty, that is, if a suspension of dirt, foreign particles exist, the solution is filtered through a 65 mesh or finer sieve. The limiting factor on the reusability of the solution is its dirtiness. Therefore, after treatment of a plurality of liners, it is suggested that the solution be filtered.
  • the aqueous solution of calcium nitrate was quickly poured in a time period of approximately 5 to 7 seconds, into a liner 10 which had been fired to remove residual pattern wax. The solution was then immediately poured out of the liner without allowing any soak time. The total lapsed time required to perform the steps of pouring the alkaline earth solution into and out of the liner 10 was less than two minutes.
  • the solution was poured over the entire area of the lip 20 of the liner. This was done by twirling or rotating the liner 10 as the solution was poured out of the liner. By pouring the solution out over the entire lip 20 of the liner 10, whenever molten metal is poured out of the liner it will flow over a portion of the lip which has been impregnated with the alkaline earth.
  • aqueous alkaline earth solution had been poured out of the liner 10, it was inverted and dried for a period of more than 15 minutes.
  • a batch or group of treated liners 10 were then transferred to a preheat furnace which had been stabilized at a temperature of 1,500 to 1,800°F.
  • the liners 10 were fired for a second time, at a temperature in excess of 1500°F for approximately one hour. This resulted in the formation of an oxide of the alkaline earth, that is calcium oxide, on the inside of each of the liners. After the liners had been removed from the furnace and cooled, they were ready for use in crucibles.
  • the alkaline earth magnesium has also been used.
  • the refractory liner 10 was impregnated with calcium oxide by quickly pouring an aqueous solution of the alkaline earth into and out of the liner.
  • other methods of impregnating the liner 10 with the alkaline earth could be used if desired.
  • the treated and fired refractory liner 10 is placed in a crucible in a manner similar to that disclosed in U.S. Patent No. 3,401,227.
  • the crucible liner 10 is then partially filled with a nickel chrome alloy.
  • An induction coil surrounding the crucible liner 10 is energized to melt the nickel chrome alloy.
  • the molten alloy is exposed to both the refractory material which forms the base of the liner and the alkaline earth which has been deposited on the refractory material.
  • the molten alloy can react with the refractory liner and the alkaline earth.
  • the reaction products remain at the reaction site, that is at the surface 11 of the liner 10.
  • the reaction products adhere tightly to the surface 11 of the liner with the resulting formation of a relatively thick layer of reaction product on the inside of the liner.
  • a relatively thin, partially adherent and discontinuous layer of reaction product remains on the untreated liner after pouring of a nickel chrome alloy.
  • the thin reaction layer remaining in an untreated crucible liner 10 after pouring of the nickel chrome alloy PWA 1422 (Mar-M200 plus hafnium) is schematically illustrated in Fig. 2.
  • the surface 11 of the refractory base 24 of the untreated liner is substantially, but not entirely, covered with a relatively thin layer 26 of reaction product. In the one specific instance-illustrated in Fig. 2, the this thin layer 26 of reaction product had a thickness of approximately 0.00005 inches.
  • reaction layer 26 on the untreated refractory base 24 of the liner of Fig. 2 is relatively thin, it is partially adherent and the molten nickel chrome alloy within the liner reacted with the materials of the refractory base 24 of the liner to form a substantial volume of reaction products.
  • the loose adherence of the layer 26 to the liner or refractory base 24 is shown by the spaces 28 between portions of the layer 26 and the base 24.
  • a refractory base 32 of a liner 10 which has been treated with an alkaline earth and a relatively thick reaction layer 34 is shown schematically in Fig. 3.
  • the molten nickel chrome alloy PWA 1422 in the liner 10 was exposed to both the refractory base material 32 of the liner and calcium deposited on the refractory base by using an aqueous solution in the manner previously explained.
  • the molten nickel chrome alloy reacted with both the refractory base 32 and the alkaline earth to form reaction products which were deposited on the inner side surface of the liner 10.
  • these products adhered tightly to the inner side surface 11 of the liner with a resulting thick layer 34 of reaction product.
  • the. reaction layer 34 had a thickness of approximately 0.0005 inches.
  • the reaction layer 34 which tightly adhered to the treated liner base 32 of Fig. 3 has a thickness which is ten times as great as the reaction layer 26 which is formed on the untreated liner base 24 of Fig. 2.
  • the reaction layer which remains in a refractory liner which has been impregnated with an alkaline earth is at least twice as great as the thickness of a reaction layer which remains in an untreated crucible liner.
  • the specific thickness of the reaction layer which remains on the sidewall of a treated crucible liner after pouring of molten nickel chrome alloy from a crucible will vary depending upon the purity of the alloy and the composition of the alloy.
  • the nickel chrome alloys which are melted in crucible liners impregnated with an alkaline earth in accordance with the present invention will be used to cast articles which are used under severe operating conditions, such as blades and vanes for gas turbine power plants in the manner disclosed in U.S. Patent No. 3,260,505.
  • a total of ten molds of twelve blades each were cast with a nickel chrome alloy.
  • the blades were JT9D-7R second stage blades. All ten of the molds were cast of the same alloy.
  • the alloy was PWA 1455 having a composition in accordance with United Technologies Corporation specifications and corresponding generally to B1900 alloy with hafnium.
  • the molten nickel chrome alloy (specifically PWA 1455) for five of the ten molds was poured from refractory liners which had been impregnated with calcium in the manner previously described herein.
  • the other five molds were filled with the same alloy poured from refractory liners which were of the same composition except that they were not impregnated with calcium.
  • the results obtained from the pouring was as follows:
  • JT9D-7A second stage vanes and JT9D-7R4 third stage vanes have been cast of the PWA 1455 nickel chrome alloy using liners impregnated with calcium. In each case, improved yield results were obtained.
  • the refractory crucible liner may be impregnated with magnesium rather than calcium.
  • the nickel chrome alloy 713C was poured from a crucible liner impregnated with magnesium into a mold to cast a jet engine component.
  • the present invention provides a new and improved crucible liner 10 which promotes the adherence of a relatively thick reaction layer 34 to the inside of the liner during pouring of a nickel chrome alloy, such as PWA 1455.
  • the liner 10 is formed of a refractory material and is impregnated with an alkaline earth.
  • the liner 10 may be impregnated with an alkaline earth, such as calcium oxide or magnesium oxide, by pouring an aqueous solution of the alkaline earth into and out of the liner before it is fired.
  • the alloy When a nickel chrome alloy is melted in the crucible 10, the alloy reacts with the alkaline earth and the refractory material of the liner. During pouring of the molten alloy, an interaction between the alloy, the alkaline earth and the refractory material maintains a relatively thick reaction layer 34 on the inner side surface 11 of the liner 10. This prevents the reaction products from entering a mold and promoting the formation of defects in a cast article.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
EP83302991A 1982-06-28 1983-05-24 Revêtement de creuset et procédé de fabrication ainsi que son utilisation Withdrawn EP0096985A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US39317782A 1982-06-28 1982-06-28
US393177 2003-03-20

Publications (1)

Publication Number Publication Date
EP0096985A1 true EP0096985A1 (fr) 1983-12-28

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EP83302991A Withdrawn EP0096985A1 (fr) 1982-06-28 1983-05-24 Revêtement de creuset et procédé de fabrication ainsi que son utilisation

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EP (1) EP0096985A1 (fr)
JP (1) JPS5921979A (fr)
IL (1) IL68865A0 (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1990593A1 (fr) * 2007-04-30 2008-11-12 General Electric Company Creusets pour la fusion d'alliages de titane
US8236232B2 (en) 2007-04-30 2012-08-07 General Electric Company Methods for making reinforced refractory crucibles for melting titanium alloys
US8708033B2 (en) 2012-08-29 2014-04-29 General Electric Company Calcium titanate containing mold compositions and methods for casting titanium and titanium aluminide alloys
US8858697B2 (en) 2011-10-28 2014-10-14 General Electric Company Mold compositions
US8906292B2 (en) 2012-07-27 2014-12-09 General Electric Company Crucible and facecoat compositions
US8932518B2 (en) 2012-02-29 2015-01-13 General Electric Company Mold and facecoat compositions
US8992824B2 (en) 2012-12-04 2015-03-31 General Electric Company Crucible and extrinsic facecoat compositions
US9011205B2 (en) 2012-02-15 2015-04-21 General Electric Company Titanium aluminide article with improved surface finish
US9192983B2 (en) 2013-11-26 2015-11-24 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9511417B2 (en) 2013-11-26 2016-12-06 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9592548B2 (en) 2013-01-29 2017-03-14 General Electric Company Calcium hexaluminate-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US10391547B2 (en) 2014-06-04 2019-08-27 General Electric Company Casting mold of grading with silicon carbide

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3401227A (en) * 1966-02-09 1968-09-10 Trw Inc Liner for crucibles
GB2019988A (en) * 1978-03-09 1979-11-07 Cockerill Protecting refractory walls
EP0065034A1 (fr) * 1981-05-16 1982-11-24 Chamotte- und Tonwerk Kurt Hagenburger Procédé de garnissage de récipients comportant un revêtement réfractaire

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3401227A (en) * 1966-02-09 1968-09-10 Trw Inc Liner for crucibles
GB2019988A (en) * 1978-03-09 1979-11-07 Cockerill Protecting refractory walls
EP0065034A1 (fr) * 1981-05-16 1982-11-24 Chamotte- und Tonwerk Kurt Hagenburger Procédé de garnissage de récipients comportant un revêtement réfractaire

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8236232B2 (en) 2007-04-30 2012-08-07 General Electric Company Methods for making reinforced refractory crucibles for melting titanium alloys
EP1990593A1 (fr) * 2007-04-30 2008-11-12 General Electric Company Creusets pour la fusion d'alliages de titane
US8858697B2 (en) 2011-10-28 2014-10-14 General Electric Company Mold compositions
US9011205B2 (en) 2012-02-15 2015-04-21 General Electric Company Titanium aluminide article with improved surface finish
US9802243B2 (en) 2012-02-29 2017-10-31 General Electric Company Methods for casting titanium and titanium aluminide alloys
US8932518B2 (en) 2012-02-29 2015-01-13 General Electric Company Mold and facecoat compositions
US8906292B2 (en) 2012-07-27 2014-12-09 General Electric Company Crucible and facecoat compositions
US8708033B2 (en) 2012-08-29 2014-04-29 General Electric Company Calcium titanate containing mold compositions and methods for casting titanium and titanium aluminide alloys
US8992824B2 (en) 2012-12-04 2015-03-31 General Electric Company Crucible and extrinsic facecoat compositions
US9803923B2 (en) 2012-12-04 2017-10-31 General Electric Company Crucible and extrinsic facecoat compositions and methods for melting titanium and titanium aluminide alloys
US9592548B2 (en) 2013-01-29 2017-03-14 General Electric Company Calcium hexaluminate-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9511417B2 (en) 2013-11-26 2016-12-06 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9192983B2 (en) 2013-11-26 2015-11-24 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US10391547B2 (en) 2014-06-04 2019-08-27 General Electric Company Casting mold of grading with silicon carbide

Also Published As

Publication number Publication date
IL68865A0 (en) 1983-10-31
JPS5921979A (ja) 1984-02-04

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Inventor name: PERRON, JAMES S.

Inventor name: JAYARAMAN, GOWRI S.